Snap acting trigger switch



July 28, 1964 G, BURY 3,142,741

SNAP ACTING TRIGGER SWITCH Filed July 11, 1962 2 Sheets-Sheet 1 INV ENTOR.

Georye Bu ry y 8, 1964 G. BURY 3,142,741

. SNAP ACTING TRIGGER SWITCH Filed July 11, 1962 2 Sheets-Sheet 2 INVENTOR.

George Bury Unite This invention relates in general to a switchconstruction, and more particularly, relates to a manually actuatedswitch construction of the snap acting variety.

It has long been desired to have a simple, safe-economical snap actingswitch for association with power tools and the like. Switchesassociated with electrically powered tools, which have a pistol likegrip, often are called trigger switches due to their actuation by asqueezing action on the part of the operator.

It is a general object of this invention to provide an economicalunitary compact snap acting trigger switch for association withelectrically powered tools and the like.

It is a further object of this invention to provide a trigger switchwhich eliminates complicated linkage mechanisms, is easy to assembly perse, and in turn is easy to assemble on the equipment it is designed toactuate.

It is a further object of this invention to provide a trigger switch asabove set forth which has a manually engageable portion made ofinsulating material, which prevents any possibility of electricalcontact by the operator through the trigger.

It is still another object of this invention to provide quick connectterminal means integral with the contact means of the switch which aidsin assembly of the electrical connection to the switch.

While the particular structural features of the specific embodimentshown in the drawings are important, it is to be understood that theprecise feature shown and described may be varied with the broaderaspects of the invention. To acquaint those skilled in the art with theform of construction of the invention, the invention will now bedescribed in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of one type of portable electricallypowered tool utilizing a switch which is the subject of the invention;

FIG. 2 is a plan view of the chambered base portion of the switch withthe trigger assembled thereto and the cover being removed;

FIG. 2A is a sectional view of the chambered base portion only alonglines 2a-2a of FIG. 2;

FIG. 3 is a view in detached relationship of the movable contact meansof the instant assembly;

FIG. 4 is a view of the trigger mechanism in detached relationship fromthe base and the cover;

FIG. 5 is a sectional view along liens 5-5 of FIG. 4;

FIG. 6 is an elevational view along lines 66 of FIG. 5; and

FIG. 7 is a plan view of the inside surfaces of the cover for the switchin detached relation.

Many types of electrical devices such as portable tools and the likeutilize a trigger mechanism to actuate the tool. A portable tool 10 inthe form of a drill having a trigger switch mechanism 12 associatedtherewith is electrically actuated by conventional electrical motorpower means (not shown) through electrical wires 14. The switch 12 isassociated with the handle or butt mechanism of the powered tool withonly the trigger portion of the switch extending exteriorly of thecasing.

While the instant switch 12 is shown associated with a portableelectrically powered tool such as a drill, this showing is to beconsidered illustrative rather than limit- States Patent 0 3,142,741Patented July 28., 1964 ing. It is, of course, contemplated that theinstant switch may be associated with many other devices requiring atrigger electrical actuation.

The switch 12 per se comprises a chambered base portion 16, preferablymolded out of an insulating plastic material such as sold under thetrade name of Lexan, nylon, or materials having similar moldablechemical compositions, electrical insulation properties, and strengthcharacteristics. The switch further comprises a minimum number of partssuch as a trigger 18 molded out of similar plastic material, a moldedcover 20, movable electrically conductive contact means 22, and fixedelectrically conductive snap acting contact means 24. Two additionalparts, namely, a pivot pin 128 and a spring 148 may be used in theconstruction depending on requirements of the environment and the exactconfiguration of the snap acting movable contact means 24 as shallbecome apparent through later discussion.

The chambered base portion 16 is formed with three major bosses 26, 28and 30 having coplanar top surfaces, the bosses 26 and 30 in effectproviding the side Walls of the switch chamber 17, the center T-shapedboss 28 aiding in providing contact location and mounting functions asshall become apparent. Upstanding bosses 26, 28 and 30 are provided withfour spaced shallow bores 34, 36, 38 and 40, which are adapted toreceive lugs 34a, 36a, 38a and 40a respectively projecting from thecover means 20 upon assembly of the corresponding lugs into therespective bores of the chambered base means. The switch chamber 17 isformed having a first opening 25 adjacent the top as shown in FIG. 2 anda second opening 27 adjacent the bottom for receipt of the terminal endof the wires which are connected through the switch. The chamber 17 hasthree separated subchambers 19, 21, and 23 formed by T-shaped boss 28,the chambers 19 and 21 being substantially isolated from each other andfrom chamber 23. A web of material 42 is associated with the right handside of the base 16 as shown in FIGS. 2 and 2A, which is provided with apair of spaced bores 44 which are adapted to mount the switch 12 withsuitable fastening means interiorly of the handle for the portable tool.Other and different mounting means can, of course, be provided for theswitch 12 as suitable and desired.

Outboard of boss 36 (to the left as viewed in FIG. 2) is a curvilinearedge surface 4-6 spaced from boss 30 by a varying width thin web section48. Curvilinear edge surface 46 may be'varied to suit and is generallyaligned with the edge surface of the handle of the tool to which theswitch is assembled. Cover 20 has an edge surface 50 which iscomplementary to edge surface 46. Upon assembly of the cover 20 to thebase with glue, heat sealing, etc., a web portion 52 of the covercorresponding to portion 48 and together with portion 48 and boss 30,form a U-shaped channel for receipt of one arm of the movable trigger 18as shall become apparent.

At the upper portion of base 16, as shown in FIG. 2, is a subportion 54of boss 26 which defines one of the outboard edges to the opening 25,the opening being smaller than the interior of the chamber 21 as shownby the offset base surface 55. The opening 25 is defined by surface 55,the subportion 54 of the boss 26 and the upper end of the side wall boss3% having the hook-like surface as shown in plan view in FIG. 2. Thisopening 25 is filled by the hub of the bell crank lever means formingthe trigger 18 of the switch so that subchamber 21 is substantiallyisolated from the exterior.

As viewed in FIG. 2, the right hand side wall boss 26 has a portion 56which is disposed substantially parallel to subportion 54 and serves asa stop portion for the limiting movement of the movable contact means22.

Extending downwardly as viewed in FIG. 2 is portion 58 of the boss 26which terminates in a hook portion 69, which together with hook portion62 of sidewall boss 30 form the second opening 27 or entrance to theswitch chamber 17. Side wall boss 30 has a laterally extending abutmentportion 64 which serves as a limiting stop for engagement of one arm ofthe trigger member 18. immediately above portion 64 is an ofiset portion66 for receipt of one end of a coil return spring means 148. Boss 30also has an upper portion 68, which together with portion 70 helpsconfine and mount the movable contact means along with the small islandbosses 84 and 86. End surface 72 of boss 31] adjacent opening 25 servesas a stop for the second arm portion of the trigger means 18 in limitingmovement of the trigger 18 in an outward direction.

The T-shaped interior boss portion 28 has a stem portion 74 as shown inFIG. 2, which effectively separates the incoming and outgoing leads 151)and 152 for actuating the electric motor (not shown). The cross portionof the T-shaped boss 28 has an angular side wall portion 76 and acut-out portion 78 for mounting retention of the end 88 of fixed contactmeans 24. Corner 80 on the boss means 28 helps confine and mount themovable contact means 22. Thus, three island bosses 82, 84 and 86together with the side wallsof the bosses 26, 28 and 38 confine andmount the movable contact means 22 and fixed contact means 24 as shownin FIG. 2 interiorly of the switch and without separate fastening means.

The fixed contact means 24 essentially comprises a flat resilient springmember made of conductive material such as beryllium copper'or the likehaving a bent end portion 88 which is angularly disposed to straightportion 90. Portion 88 is disposed in the cut-out 78 of boss 28 andportion 90 is disposed adjacent to angularly disposed portion 76 of theT-shaped boss 23. A tongue 92 is struck out of the center of the fixedcontact means 24 and is configured so that the free end portion 94 isdisposed adjacent to one wall of boss portion 74, the side edgesremaining after blanking out of the tongue 92 being disposedintermediate the island boss 82 and portion 60 of boss 26 for retentionpurposes. The end 98 of the fixed contact means 24 is disposed inopposed relation to portion 94, said end 98 being resiliently biasedaround island boss 82 and towards portion 94 so that mere insertion ofthe stripped portion of an insulated wire 152 will quickly andconveniently make an electrical connection to the fixed contact means24. Portion 90 forms the fixed contact of the electrical assembly andmay be used as is or may have a special contact surface disposed thereonas suitable and desired. It will be appreciated that the fixed contactmeans 24 is merely slipped into place and is fixedly held confinedbetween the various bosses, no other mounting means being required tohold it in place interiorly of the switch.

The movable contact means 22 is also preferably formed of flat thinspring stock also of a material similar to beryllium copper or the like.Movable contact means 22 has a free end portion 100 mounting a contact102 near the center thereof. A tongue 104 is blanked out of the contactmeans 22 to provide a free end 105 and a pair of spaced arm portions 166and 108. Contact means 22 further has a portion 110 which is angularlydisposed to portions 104, 106, and 108, and is suitably confined betweenisland boss 86 and boss portion 68 of boss 30, said portion 110 beingfurther confined between corner 80 of boss 28 and boss portion 69 ofboss 30. A tongue 112 is struck out of movable contact means similarlyto tongue 92 and extends towards tongue 92 having a mirror imagerelationship thereto. End portion 114 of the tongue portion 112 isdisposed on the opposite side of portion 74 of boss 28 to portion 94 ofthe fixed contact means. Portions 116 and 118 of the terminal end of themovable contact means correspond to portions 96 and 98 of the fixedcontact means to provide a suitable quick connect attachment means foran insulated conductor which has been stripped at the end portion suchas is shown at 150 in FIG. 2.

Manually engageable trigger 18 is in the form of a bell crank leverhaving an elongated first arm portion 120 and a shorter arm portion 122.The apex or hub of the arms 118 and 122 is formed with a bore havingcounterbores 124 and 132 for receipt of lugs 126 and 127 which arerespectively molded on the cover 20 and the chambered base portion 16. Apivot pin 128 is mounted through the annular bosses 126, 127, and isdisposed in bore 138 to pivotally mount the trigger 18 so that the arm122 extends into opening 25 for coaction with the movable contact means.Under some circumstances, the pin 128 may be molded integrally into thebase 16 or cover 20. Surface 134 of arm 120 is curvilinear and isadapted to be engaged by the finger. Portion 129 of the trigger means 18is formed with a pair of slightly offset surfaces 136 and is furtherformed with a cut-out 138 for receipt of the other end of the springmeans 148. It will be appreciated that spring 148 is adapted to beinserted between cut-out 136 of the trigger and cut-out 66 of boss means30 of the base portion 16. It will also be realized that depending uponthe snapacting type of mechanism used in the movable contact means, thespring 148 may or may not be necessary since the force of the tongue1114 may provide sufiicient return force for the trigger.

Arm portion 122 of the trigger 18 has an end portion 140 and a dependinghook-like portion 144 which describes a curvilinear fillet 142therebetween. A shoulder surface 146 is disposed on the end of portion144 for receipt of the end 105 of the tongue 184 of the movable contactmeans. The fillet 142 is adapted to be engaged by a pin disposed asindicated in dotted lines at 143 to lock the trigger in its dottedposition.

After the parts are assembled as shown in FIG. 2, it will be seen thatthe movable contact 102 is normally biased against surface 56 of boss 26by the coaction of end 105 of tongue 104 of the movable contact meanswith shoulder 146 of the trigger 18. Further, spring 148 also biases thetrigger 18 to the full line position shown in FIG. 2. Movement of armportion 118 tothe right as viewed in FIG. 2, as by the manual squeezingpressure of a finger on a trigger, causes the trigger 18 to pivot aboutpin 128 to in turn cause the end 105 to move to the position shown indotted lines in FIG. 2. This movement causes the contact 102 to snapover center and move into engagement with fixed contact means 24 atportion 90. This will make the electrical connection between incomingand outgoing wires 150 and 152. It will be realized that all parts areplastic in this device except for the pin 128, the spring 148, and thecontact means 22 and 24. Thus, it is apparent that the operator of thedevice cannot receive an electrical shock through the trigger 18. Itwill be further realized that the depiction of the switch in thedrawings are considerably exaggerated in size and that in point of factthe switch 12 is of a very compact nature. It will be further seen thatthe device has a minimum number of parts which are carefully arrangedfor ease of assembly. The absence of complicated lever mechanisms andsmall number of parts provide a long and trouble-free field life whichis admirably suited for association with power tools and the like.

While a specific embodiment of the invention has been shown anddescribed, it is with full awareness that many modifications arepossible. The invention, therefore, is not to be restricted except in sofar as is necessitated by the prior art and by the spirit of theappended claims.

I claim:

1. A switch for association with an electrically powered portable toolor the like comprising molded insulated housing means comprisingchambered base means and cover means assembled together to define firstand second spaced openings, pivot means located adjacent said firstopening and associated with said base means and cover means, manuallyengageable pivotal bell crank lever means having first and secondangularly disposed arms mounted on said pivot means with said second armextending into said first opening, fixed contact means mounted in saidchambered base means having a terminal portion extending adjacent saidsecond opening, movable contact means comprising an angularly bent fiatspring member having a first portion carrying a movable contact adjacentthe free end thereof and a second portion disposed adjacent to andspaced from the fixed contact means portion and adjacent to said secondopening, said spring member having a third portion intermediate saidfirst and second portions engageable with said second arm of said belllever and adapted to impart snap action movement to said contact on saidfirst portion, and spring means interposed between said first armportion of said bell crank lever means and said chambered base portionbiasing said bell crank lever means to a first position, whereby movement of said first arm of said bell crank lever means against saidspring means causes said second arm to move said movable contact meansrelative to said fixed contact means with a snap like action.

2. A trigger switch for association with an electrically poweredportable tool or the like comprising molded plastic housing means havinga chambered base means and cover means assembled together to define anirregularly shaped chamber having greater width and length thanthickness and having first and second spaced openings in the side wallsdefining the thickness of the housing, pivot means located adjacent saidfirst opening and mounted between said base means and cover means,manually engageable pivotal bell crank lever means having a first fingerengageable arm and a second angularly disposed arm mounted on said pivotmeans with said second arm extending into said first opening, said levermeans being movable in a plane parallel to said cover means, fixedcontact means comprising an elongated thin flat spring member fixedlymounted in said switch chamber having a terminal portion extendingadjacent said second opening, said terminal portion having a quickconnection means for association with electrical conductors, movablecontact means comprising a second angularly bent flat spring memberhaving a first movable portion carrying a contact adjacent the free endthereof and a second portion disposed adjacent to and spaced from theterminal portion of said fixed contact means adjacent to said secondopening, said second portion also having quick connection means forassociation with electrical connectors, said second spring member havinga third portion blanked out of a fourth portion located intermediatesaid first and second portions to provide a stressed tongue engageablewith said second arm of said bell lever adapted to impart snap actionmovement to said contact on said first portion, and compression springmeans interposed between said first arm portion of said bell crank levermeans and said side walls of said chambered base portion biasing saidfirst arm of said bell crank lever means outwardly therefrom, wherebymanual squeezing movement of said first arm of said bell crank levermeans against said spring means causes said second arm to move saidmovable contact means relative to said fixed contact means with a snaplike action.

3. A trigger switch comprising chambered base means and cover meansassembled together to define a switch enclosure having first and secondspaced openings, pivot means located adjacent said first opening andmounted between said base means and cover means, manually engageablepivotal bell crank lever means having first and second angularlydisposed arms mounted on said pivot means with said second arm extendinginto said first opening, fixed contact means mounted in said switchenclosure having a terminal portion extending adjacent said secondopening, movable contact means comprising a member having a firstportion carrying a contact engageable with said fixed contact means anda second portion disposed adjacent to and spaced from the terminalportion of said fixed contact means adjacent to said second opening,said member having a third portion intermediate said first and secondportions engageable with said second arm of said bell lever to impartsnap action movement to said contact on said first portion, wherebymovement of said first arm of said bell crank lever means causes saidsecond arm to move said movable contact means relative to said fixedcontact means with a snap like action.

4. The trigger switch set forth in claim 3 wherein the terminal portionof the fixed contact means has a tongue portion blanked out of arelatively straight portion and angularly bent in opposition thereto toprovide quick connection means for a wire conductor, and said secondportion of said movable contact means is formed similarly to saidterminal portion of said fixed contact means to form a quick connectionmeans for a second wire conductor or the like.

5. The trigger switch set forth in claim 3 wherein said chambered basemeans has an internal T-shaped boss means having an opening therein forengaging and mounting one end of said fixed contact means, the longportion of said T-shaped boss means providing an insulating separator tosaid terminal portion of said fixed contact means and said secondportion of said movable contact means adjacent said second opening.

6. The switch set forth in claim 3 wherein said second arm of said bellcrank lever means has a depending portion disposed substantiallyparallel with said first arm of said bell crank lever means, saiddepending portion being formed with a shoulder engageable with saidthird portion of said movable contact means to impart snap actionmovement to said contact on said first portion of said movable contactmeans.

7. The trigger switch set forth in claim 6 wherein said dependingportion of said second arm portion is located intermediate the ends ofsaid second arm, the end of said second arm away from said pivot pointproviding an abutment engageable with a locking means to hold said bellcrank lever in a fixed position.

8. The trigger switch set forth in claim 3 wherein said chambered basemeans has a plurality of boss means providing side walls to said switchenclosure, said chambered base means further having a plurality ofisland boss means located closely adjacent to said side wall boss meansto confine and mount the fixed and movable contact means therebetweenfor retention of the fixed and movable contact means in operativeposition without the use of fastening means.

9. The switch set forth in claim 3 wherein said chambered base means hasa first boss means defining a side wall to said switch enclosure, saidbase means having a web portion extending exterior of said first bossmeans, and when assembled with said cover means defines a U-shapedchamber for receipt of said first lever arm upon actuation of said firstlever arm in a plane substantially transverse to said first boss meansand parallel to said cover means and said web portion of said chamberedbase means.

10. The switch set forth in claim 9 wherein said chambered base meanshas a second web portion extending outwardly from the side opposite tosaid first boss means, said second web portion being provided withmounting holes for mounting said switch.

11. The trigger switch set forth in claim 3 wherein said chambered basemeans, said cover means, and said manually engageable bell crank levermeans are formed of plastic material having insulating characteristics.

No references cited.

3. A TRIGGER SWITCH COMPRISING CHAMBERED BASE MEANS AND COVER MEANSASSEMBLED TOGETHER TO DEFINE A SWITCH ENCLOSURE HAVING FIRST AND SECONDSPACED OPENINGS, PIVOT MEANS LOCATED ADJACENT SAID FIRST OPENING ANDMOUNTED BETWEEN SAID BASE MEANS AND COVER MEANS, MANUALLY ENGAGEABLEPIVOTAL BELL CRANK LEVER MEANS HAVING FIRST AND SECOND ANGULARLYDISPOSED ARMS MOUNTED ON SAID PIVOT MEANS WITH SAID SECOND ARM EXTENDINGINTO SAID FIRST OPENING, FIXED CONTACT MEANS MOUNTED IN SAID SWITCHENCLOSURE HAVING A TERMINAL PORTION EXTENDING ADJACENT SAID SECONDOPENING, MOVABLE CONTACT MEANS COMPRISING A MEMBER HAVING A FIRSTPORTION CARRYING A CONTACT ENGAGEABLE WITH SAID FIXED CONTACT MEANS ANDA SECOND PORTION DISPOSED ADJACENT TO AND SPACED FROM THE TERMINALPORTION OF SAID FIXED CONTACT MEANS ADJACENT TO SAID SECOND OPENING,SAID MEMBER HAVING A THIRD PORTION INTERMEDIATE SAID FIRST AND